Control system to produce cyclical rotary motion



Sept. 16, 1969 w, J. TH 5RN .L ETAL 3,467,905

CONTROL SYSTEM TO PRODUCE CYCLICAL ROTARY MOTION Filed Oct. 22. 1965 ISGNAL s 4- Sheets-Sheet 1 PULSE GENERATOR INTEGRATOR ACTUATING MECHANISMINTEGRATOR I8 39 I 36 38 2| 22 2a 24 s I S i ACCUM. "MR 40 42 37 I5 1 l6AIR OUT 20 FIG. 2

INVENTORS w. J. THORNHILL BY R.o. WELTY A 7' TOR/VEYS Filed Oct. 22,1965 FIG. 3

PRESSURE PSIG Sept. 16, 1969 W.J.THORNHILL ETAL 3,467,905

CONTROL SYSTEM TO PRODUCE CYCLICAL ROTARY MOTION 4Sheets-Sheet z 14 PSIGIN PIPE 44 7 PSIG IN PIPE |o- PRESSURE SWITCH 3o ACTUATION PRESSURE 8 6PSIG E A TTORNEVS Sept. 16, 1969 CONTROL SYSTEM TO PRODUCE CYCLICALROTARY MOTION Filed Oct. 22. 1965 980 I 1 I88 I I I03 4 Sheets-Sheet ZLATCHING 82 RELAY 80 F/G. 5A

INVENTORS J. W. THORNHILL R0. WELTY Sept. 16, 1969 w, THQRNHlLL ETAL3,467,905

CONTROL SYSTEM TO PRODOCE CYCLICAL ROTARY MOTION 4 Sheets-Sheet 4 FiledOct. 22. 1965 mm MWY ERU vm m W0 R m l 6 w F 8 G I F b m o 5 m 1 m a. b

7f ATTO/PNEYS United States Patent 3,467,905 I CONTROL SYSTEM TO PRODUCECYCLICAL ROTARY MOTION William J. Thornhill and Richard O. Welty,Bartlesville,

Okla., assignors to Phillips Petroleum Company, a corporation ofDelaware Filed Oct. 22, 1965, Ser. No. 502,096 Int. Cl. H02p 1/04; H02h7/08 US. Cl. 318443 9 Claims ABSTRACT OF THE DISCLOSURE In order toautomatically add measured amounts of a catalyst or other substance to achemical reaction as needed, a signal representing a specific reactioncondition is utilized to generate a pulse which has a widthrepresentative of the magnitude of said signal. An integrator then addsthe pulses and after a predetermined total pulse time triggers anactuating mechanism which performs the operations necessary to add asubstance to the chemical reaction.

' a substantially constant time interval, the time intervals beingsubstantially equal, and then converting this intermediate signal ofvariable duration-constant time interval pulses to the desired resultingsignal of variable time interval-constant duration pulses. In anotheraspect, this invention relates to a method and apparatus above and inaddition to method and apparatus for utilizing the resulting signal toeffect and control a cyclic mechanical, preferably a rotary, motion. Instill another aspect, this invention relates to apparatus for convertingthe above resulting signal to a cyclic rotary motion composed of asequence of rotation of a member through a finite are, holding themember still for a finite period of time, and then rotating said memberin a second finite arc.

In US. Patent 3,167,398, the disclosure of which is hereby incorporatedherein by reference, there is disclosed metering apparatus comprising arotatable member having a chamber extending therethrough, and means toalternately accumulate and discharge through said chamber as the memberis rotated measured amounts of material thereby insuring accurate andcontrolled feed rate of that material, e.g. catalyst, to a receiver,e.g. a polymerization reactor. The operation of such metering devicesrequires the rotatable member to be rotated through a finite arc toaline the chamber therein with the inlet and exit apertures of thedevice, pause a finite length of time to allow substantially completedischarge of the material in the chamber through the exit aperture andcharging of a second chamber to be subsequently discharged, and thenrotated through another finite arc to move and hold the chamber fromcommunication with the exit aperture until another measured amount ofmaterial is desired to be discharged. Generally, the cycle rate of suchmetering devices is presently manually set by an operator and remains atthe set cycle rate until reset by an operator regardless of changes inthe process which the device is feeding. These changes generally requirea change in the feed rate, i.e.cycle rate of the device, thereto. Thus,it is extremely important to have an operation ice wherein the cyclerate of the metering device is responsive to at least one processvariable and/or at least one property of the product.

However, it was found that conventional cyclic actuators could noteffect a sufiiciently lengthy pause between the two arcs of rotation inthe cycle of the metering device and therefore did not allow sufficienttime for the chamber of the metering device to completely discharge thedesired quantity of material. Attempts to adjust these conventionalactuators only resulted in jerky, erratic motion causing considerableleakage of the metering device as well as increased wear and generallypoor performance of that device.

According to this invention there is provided a method and apparatuswhereby the proper cyclic operation, and particularly a proper timelength pause between the two arcs of rotation in each cycle, is effectedso that the chamber of the metering device is substantially completelyempty and the measured feed rate objective of the metering device isrealized.

Broadly, a method of this invention involves producing a signal ofvariable time interval-constant duration pulses which signal is inproportion to a signal representative of a measured process variableand/or a property of the product. This method includes first producing asignal of variable duration-constant time interval pulses which signalis proportional to the signal representative of the process and/ orproperty and then converting that signal to the desired signal ofvariable time interval-constant duration pulses.

By variable duration-constant time interval pulses, it is meant asignal, be it electrical, hydraulic, pneumatic, and the like, which isbroken up into substantially constant time intervals and during eachtime interval there is produced a pulse, eg a flow of electrons, etc.,which will last for a variable time duration depending upon themagnitude of the signal representative of the process variable and/orproperty measured, but the maximum of which duration is equal to or lessthan the time interval in which that pulse is produced. For example, ifthe time interval is 10 seconds, a pulse produced during that timeinterval can vary from 0 to 10 or slightly less than 10 seconds and ifthe signal representative of the process variable and/or propertyincreases in magnitude, e.g. in the case of pneumatic signal increasesin pressure, the time duration of each pulse in each time interval willincrease toward the 10-second maximum until the first signal remainsconstant or decreases in magnitude in which case the time duration ofeach pulse in each time interval will become constant or decrease inlength, respectively. By variable time interval-constant durationpulses, it is meant a signal wherein each pulses produced lasts for thesame time duration but that each substantially constant time durationpulse is separated from the other by a variable time interval so that asthe time duration of each pulse in the variable time duration-constanttime interval signal increases in response to increased magnitude of thesignal representative of the process variable and/or property, the timeinterval between the constant duration pulses in the variable timeinterval-constant duration pulse signal becomes less and therefore is inproportion to the magnitude of the first signal representative of theprocess variable and/or property. Generally, the first signal as withthe other signals mentioned above can be electrical, pneumatic,hydraulic and the like, and is composed of a pulse having an indefiniteand variable time duration and having a varying magnitude during thattime duration.

Further according to the method of this invention, the variable timeinterval-constant duration pulse signal is employed to effect and tocontrol the cyclic operation; i.e. rotation through a first arc, pause,rotation through a secnd arc, hold; necessary to operate the abovemetering device.

The apparatus of this aspect of the invention includes a variableduration pulse generator which will produce a pulse during each of asequence of constant time intervals and which will vary the duration ofeach pulse in each time interval in proportion to the magnitude of thesignal responsive to the process variable and/or property measured, anintegrator which will convert the variable duration-constant timeinterval signal put out by the variable duration pulse generator into avariable time interval-constant duration signal suitable for conversionto the cyclic mechanical, preferably rotary, motion necessary to operatethe metering device.

Further according to this invention a variable duration pulse generatoris employed which during substantially equal successive time intervalsproduces a source of fluid under pressure and passes said fluid past apressure switch and out of the system. Depending upon the pressure ofthe fluid passing through the pressure switch, that switch may not closeat all or may be closed for any length of time up to the length of thetime interval during which the fluid is passed through the pressureswitch. The variable duration pulse, i.e. the time in each intervalduring which the pressure switch is closed, is accomplished by varyingthe rate of flow of the pressurized fluid through the pressure switch inresponse to the magnitude of the signal responsive to the measuredprocess variable and/ or property of the product. This apparatus canfunc. tion electrically, pneumatically, hydraulically, etc.

Also according to this invention the metering device actuating mechanismfor converting the variable time interval-constant duration signal putout by the integrator into the cyclic mechanical motion required by themetering device includes a member for rotating the rotatable member ofthe metering device which carries at least one cam means which isadapted to rotate with said member. Associated with at least one cammeans is at least one switch means which is adapted to be actuated by atleast one cam follower engaging said at least one cam means. The outputsignal from the integrator is passed to and through said at least oneswitch means. The said at least one switch means is operativelyconnected to the means for rotating the member and therefore therotatable member of the metering device both directly and through a timedelay means. The configuration of the at least one cam means is suchthat after rotation of said cam means through a finite arc, the at leastone switch is actuated thereby passing the signal from the integratorthrough the time delay means and allowing time for the chamber in themetering device to substantially completely discharge its contents and asecond chamber to be charged before the time delay device is overcomeand the signal passed to the means for rotating the member therebyrotating the cam through a second finite arc and accomplishing theoperation cycle of the metering device of rotation through a first arc,pause, and rotation through a second arc.

Accordingly, it is an object of this invention to provide a new andimproved method and apparatus for producing a cyclic mechanical motionin response to a signal representative of a measured process variableand/ or property of the product. It is another object of this inventionto provide a new and improved method and apparatus for producing avariable duration pulse-constant time interval signal proportional to asignal representative of a measured process variable and/ or property ofthe product. Another object of this invention is to provide a new andimproved apparatus for converting a variable time interval-constantduration pulse signal to a cyclic mechanical motion.

FIGURE 1 shows schematically a system embodying this invention.

FIGURE 2 shows a var able duration pulse generator of this invention.

FIGURE 3 shows graphically operational characteristics of the apparatusof FIGURE 2.

FIGURE 4 shows integrator apparatus suitable for usein this invention.

FIGURE 5 shows a metering device actuating mechanism according to thisinvention.

FIGURE 5A shows an alternative time delay means which can be used in themetering device actuating mechanism of FIGURE 5.

FIGURE 5B is a schematic electrical representation of solenoid actuatedrelay switch 98 which is shown in FIGURES 5 and 5A.

FIGURE 6 shows relative relationships of the cams of the apparatus ofFIGURE 5 during one cycle of operation.

FIGURE 7 shows a metering device actuating mechanism of this invention.

FIGURE 7A shows an alternative time delay means which can be used withthe metering device actuating mechanism of FIGURE 7.

FIGURE 8 shows the relationships of the cam of the apparatus of FIGURE 7through one cycle of operation.

FIGURE 1 shows a variable duration pulse generator 1 operativelyconnected to an integrator 2 which in turn is operatively connected tometering device actuating mechanism 3. Actuating mechanism 3 isconnected through shaft 4 to metering device 5. Signal 6 is the firstsignal or signal representative of a measured process variable and/orproperty of the product. If desired, first signal 6 can be anarbitrarily selected, manually produced signal. As an example, signal 6can be the output signal of a conventional temperature recordercontroller which is operatively connected in a conventional mannerthrough a differential thermocouple device to the interior of a pipecarrying therethrough cooling water on its way to the cooling jacket ofa polymerization reactor. If signal 6 is pneumatic, it is preferably inthe range of 3 to 15 p.s.i.g. The sensed differential temperature of thecooling water entering and leaving the jacket will determine themagnitude of the output signal of the temperature recorder controllerand its is this signal and the magnitude thereof which determines theduration of the pulse in each time interval of the intermediate signal 7put out by variable duration pulse generator 1. If the output signal ofthe temperature recorder controller is, for example, pneumatic anincrease in the pressure of this signal, representing an incease oftemperature of the monomer in the pipe, is impressed on the variableduration pulse generator and the effects thereof are shown in detail inthe discussion of FIGURE 2, infra. Signal 7 from generator 1 is thenpassed to integrator 2 which converts signal 7 to signal 8 which signalis composed of a series of pulses each of substantially the same timeduration and each separated from the other by variable time intervals.Signal 8 is then used to activate actuating mechanism 3 which convertssignal 8 to a rotary mechanical motion manifested in the rotation ofshaft 4 which in turn operates metering device 5 in the cyclical mannerrequired by that device. Metering device 5 can be that apparatusdisclosed in US. Patent 3,167,398 and similar known types of apparatus.

Thus, due to the measured change of a process variable which is passedto generator 1 in the form of signal 6 the variable duration pulse putout by generator 1 in the form of signal 7 is changed accordingly andthe variable time interval put out by integrator 2 is also changedaccordingly so that the actuating mechanism 3 which operates in responseto signal 8 is also accordingly effected and in turn operates meteringdevice 5 in relation to the elfect thereon by signal 8 thereby causingthe cyclical operation of metering device 5 to be responsive to thechange in the process variable manifested in signal 6. If thetemperature of the monomer increases above normal the pressure of thepneumatic signal 6 increases which increases the duration of each pulsein each time interval of signal 7 which shortens the time intervalbetween constant duration pulses of signal 8 which actuates mechanism 3faster than is normal with the result that metering device 5 is operatedfaster than normal.

In FIGURE 2 there is shown a variable duration pulse generator wherein acam switch is driven by a motor 11 so that for a given interval of timethe cam switch is open a part of the interval and closed another part ofthat interval, and this sequence is repeated continually therebyproducing a continuous series of substantially constant time intervals.Switch 10 and motor 11 are electrically connected by electrical lines 12and 13 so that motor 11 constantly drives cam switch 10 and when camswitch 10 is contacting element 14 an electrical circuit is closedbetween normally open solenoid valve 15 and normally closed solenoidvalve 16 by means of electrical lines 17, 18, and 19. Between valves 15and 16 is air accumulator 20 which is in open communication with valves15 and 16 through pipes 21 and 22, respectively. Accumulator 20 isopenly connected to a source of air through conduit 22, valve 16 andconduit 23. The amount of air passed into accumulator and therefore themaximum pressure of the air in accumulator 20 produced while normallyclosed valve 16 is open is controlled by needle valve 24.

Normally open pressure switch 30 is electrically connected to integrator2 through electrical lines 31, 32, and 33. Integrator 2 is alsoconnected to conduit 19 by electrical line 34. Pressure switch 30 isopenly connected through pipes 35, 36, and 37 to valve 15 andaccumulator 20. Throttle valve 38 is openly connected between pipes 36and 37 and adapted to vary the rate of flow of air from accumulator 20into pipe 36.

Pipe 36 is also in open communication with motor valve 39 through pipe40and bleed valve 41 through pipe 42. Air from accumulator 20 passes outof the system via pipe 43. The rate at which air passes out of thesystem through 43 can be varied by varying the opening of throttle valve39 in response to the magnitude of the pressure of a pneumatic airsignal passing to motor valve 39 through pipe 44. The air signal inconduit 44 is the signal that is representative of the measured processvariable and/or property of the product.

In operation and by way of example, cam switch 10 and timing motor 11are adjusted to produce a time interval of 10 seconds. That is, thesubstantially constant time intervals in the signal passed to integrator2 through line 33 is 10 seconds. During the first portion of the 10secondinterval, about 2 seconds, the cam switch is actuated bycontacting member 14 thereby closing normally open valve 15 and openingnormally closed valve 16 so that air is passed into accumulator 20 andis allowed to accumulate to a predetermined maximum pressure, in thisexample p.s.i.g. After passage of this first portion of the timeinterval cam switch 10 is deactivated by moving from contact withmember14 and normally open switch 15 is opened and normally closedswitch 16 is closed thereby allowing the pressurized air in accumulator20 to pass through pipes 21, 37, 36, 40, and 43 out of the system andalso into pipe 35 where sufiicient pressure will activate pressureswitch 30. Bleed valve 41 is adjusted so that when motor valve 39 issubstantially completely closed, the pressurized air in accumulator 20will be lowered to the actuation pressure of pressure switch before the'next 10 second interval starts and accumulator 20 is repressurized withnew air. Throttle valve 38 can be adjusted so that when motor valve 39is wide open the pressure in pipe does not reach a pressure sufficientto actuate pressure switch 30, in this example 6 p.s.i.g.,or' is justsufficiently high to actuate pressure switch 30 for only a small amountof time, for example about 3 seconds.

' Thus,.when signal 44 varies in magnitude, for example increases inpressure, the opening in motor valve 39 is pinched down to therebyrestrict the flow of air therethrough from pipe thereby increasing thepressure in pipe 35 and forcing pressure switch 30 closed for a longerperiod of time than is normal. When this is effected, a variableduration pulse, in this case of increased duration, is passed throughline 33 to integrator 2 during each 10 second time interval. Therefore,a variable durationconstant time interval signal is passed to integrator2, the variable duration pulse of that signal being responsive to thesignal in pipe 44 which in turn is responsive to the measured processvariable or property of the product. Generally, the pneumatic signal inpipe 44 will vary from a zero to 8 second duration and a 3 to 15p.s.i.g. magnitude.

If pressure switch 30 is adjusted so that under normal conditions it isclosed for a finite period of time, the pulse generator of thisinvention can send pulses of longer duration to the integrator inresponse to increased pressure of the signal in pipe 44 thereby speedingthe operation of integrator 2 or can keep pressure switch 30 open longerthan normal thereby sending pulses of shorter duration than normal tointegrator 2 thereby slowing the operation of that integrator inresponse to lower pressures than normal in pipe 44.

FIGURE 3 shows a graph wherein time is plotted against pressure onpressure switch 30 so that when accumulator 20 is charged up to a 25p.s.i.g. maximum and then allowed to pass its pressurized air out of thesystem under normal conditions, arbitrarily set as normal at a 7p.s.i.g. signal in pipe 44, pressure switch 30 will remain closed for 4seconds. However, if the signal in pipe 44 increases to a magnitude of14 p.s.i.g. in response, for example, to a temperature increase of themonomer abovementioned, motor valve 39 will be pinched down so that thepressurized air is not removed from the system until the end of the10-second time interval and therefore pressure switch 30 stays closedfor substantially the whole time interval of 10 seconds. Similarly, ifthe signal in pipe 44 should fall below the normal 7 p.s.i.g. to 5p.s.i.g., motor valve 39 will open further thereby allowing thepressurized air in accumulator 20 to pass out of the system more rapidlyand pressure switch 30 is thereby closed for only 3 seconds. Thus, itcan be seen that depending upon the magnitude of the signal in pipe 44the relation of the pulse sent to integrator 2 during each equal timeinterval will vary in direct proportion and pulse generator 1 istherefore supplying to integrator 2 a variable duration-constant timeinterval signal.

Although any type of conventional apparatus which can receive and storesignals of variable duration until a predetermined amount of thesesignals has been received and then produce a signal of constant durationpulses can be employed as an integrator of this invention, an example ofsuch apparatus is shown in FIGURE 4. In integrator 2 of FIGURE 4 thereis a timer motor which rotates a shaft 51 which in turn carries androtates two cam means 52 and 53 each with a similar indentation 54 and55 in the periphery thereof. Cam followers 56 and 57 are connected toelectrical switches 58 and 59.

The signal is transmitted from the variable duration pulse generator 1of FIGURE 2 to timer motor 50 by electrical lines 60 and 61. Switch 58is connected to an electrical power source (not shown) by electricalline 63 and to line 60 by electrical line 64. Electrical line 65connects the electrical supply source to line 61. Switch 59 is connectedthrough electrical line 70, electrical power supply 71 and electricalline 72, and electrical line 73 to the metering device, actuatingmechanism 3 (not shown).

In operation, during each 10 second time interval pulses of varyingduration pass by lines 60 and 61 to motor 50 thereby operating same andturning cams 52 and 53 for a time substantially the same as the durationof each pulse. When a suflicient number of pulses of suificient durationhave operated motor 50 long enough to cause indentations 54 and 55 tocome into register with cam followers 56 and 57 switches 58 and 59 aretripped and a pulse is sent by way of lines 72 and 73 to actuatingmechanism 3. When switch 58 is tripped the electrical sources areconnected into motor 50 thereby causing same to continue to operateuntil cam follower 56 is disengaged from indentation 54 of cam 52 atwhich time switch 59 is also deactuated and the pulse to the actuatingmechanism terminated. Thus, a variable duration pulse-constant timeinterval signal from pulse generator 1 passes into integrator 2 by lines60 and 61 and a variable time interval-constant duration pulse signal ispassed from integrator 2 by lines 72 and 73 to the actuating mechanism3.

FIGURE shows an actuating mechanism of this invention wherein thevariable time interval-constant duration pulse signal from integrator 2is passed from electrical lines 72 and 73 to latching relay 80 which isadapted by means of coil 81 to, upon receipt of a pulse from integrator2, switch contacting arm 82 from the contact on which it was left upontermination of the last received pulse (as shown in FIGURE 5 contact 83)to the other contact 84 in latching relay 80. Contacts 83 and 84 areconnected by electrical conduits 85 and 86 to contacts 87 and 88 ofswitch 89. Switch 89 is connected by electrical line 90 to switch 91.Contact 92 is connected by way of electrical line 94 to switch 120 whichhas two contacting arms 121 and 122 and three contacts 123, 124, and125. Contacts 123 and 125 are connected through lines 126 and 127respectively to line 97 for control of solenoid actuated relay switch98. Details of the operation of solenoid actuated relay switch 98 areshown in FIGURE 5B. Contact 124 is connected to the timing motor 128 byelectrical line 129. Timing motor 128 is also connected to conduit 73 byelectrical line 130. Shaft 131 of motor 128 carries cam 132 which coactswith cam follower 133 which is adapted to move contact arms 121 and 122between two of the contact points. Switch 98 is connected by electricalline 103 to electrical drive motor 104. Electrical line 186 of motor 104and 188 of switch 98 are connected to a normally on electrical powersource. Motor 104 rotates shaft 105 which shaft carries cams 106 and 107and which shaft is connected to the rotatable member of metering device5. Thus, when drive motor 104 rotates shaft 105 cams 106 and 107 and therotatable member of metering device 5 are all moved together. Camfollowers 108 and 109 engage, respectively, cams 106 and 107 and areadapted to trip switches 91 and 89 back and forth from their twocontacts.

In operation, the pulse passing through contacts 84, 88 and 92 passesthrough line 94, a contacting arm 121, contact 123 and lines 126 and 97to actuate switch 98 and start operation of motor 104. After motor 104has turned cam 106 90 it moves the contacting arm of switch 91 fromcontact 92 to 93 which causes the pulse to pass through conduit 99,contact arm 122, contact 124 and line 129 to start operation of timingmotor 128. Timing motor 128 turns cam 132 until cam 132 trips switch 120by moving contacting arms 121 and 122 into contact with contacts 124 and125, respectively. The time required to cause rotation of cam 132 sothat it will trip switch 120 is that amount of time required to allowthe chamber in the rotatable member of metering device to substantiallycompletely empty its contents. When switch 120 is tripped the pulseoriginally passing through contacting arm 122, contact 124 and line 129is then directed to contact 125 and lines 127 and 97 to reactivateswitch 98 and start motor 104 in operation again. After motor 104 hasturned cam 106 and 107 through another 90 arc contacting arm in switch91 is moved from contact 93 to 92 and the contacting arm in switch 89 ismoved from contact 88 to contact 87 and operation of the mechanismterminated. When the next pulse arrives it will be directed throughcontacts 83, 87, 92 and 124 thereby causing operation of timing motor128 until cam 132 reaches the point where it trips switch 120 back andthe pulse is then severed from contact 124 to contact 123 and therebyallows actuation of switch 98 and starts operation of motor 104, tostart a new cycle.

FIGURE 5A shows an alternative delay means which can be used to replaceswitch 120, motor 128, cam 132,

and cam follower 133 of the FIGURE 5 apparatus. Contact 92 of theapparatus shown in FIGURE 5 is connected by way of electrical lines and97a to solenoid actuated relay switch 98. Contact 93 is connected byelectrical line to circuit delay device 101, and lines 102 and 97aconnect circuit delay device 101 to solenoid actuated relay switch 98.

In the operation of the device of FIGURE 5 using this alternativecircuit delay device, a pulse received from integrator 2 causescontacting arm 82 to switch from contact 83 to 84 and pass the pulsethrough contacts 88 and 92 through lines 95 and 97a to switch- 98thereby causing it to close and start motor 104 in operation. Aftermotor 104 has rotated (together with cams 106 and 107 and rotatablemember in metering device 5) about 90, the contacting arm of switch 91is transferred from contact 92 to contact 93 thereby causing the pulseto pass into circuit delay device 101 which causes the pulse to be heldup and thereby interrupts the supply of electricity to switch 98 whichcauses that switch to return to its normally open position. The circuitdelay device 101 can be any conventionally known delay device such as aCramer Type TEC-lSS Style A time delay relay made by the R. W. CramerCompany, Inc., Centerbrook, Conn. After a short interval of time whichis sufficient in length to allow the chamber in the rotatable member ofmetering device 5 to substantially completely empty the contentsthereof, the pulse is passedby lines 102 and 97a to switch 98 whichactuates and again starts motor 104 into operation. After motor 104hasrotated cams 106 and 107 another 90, the contacting arm in switch 91is moved from contact 93 back to contact 92 and at the same time contactarm in switch 89 is passed from contact 88 to contact 87. When thecontacting arm in switch 89 is passed from contact 88 to contact 87. themechanism is deactivated and will not be reactivated until a new pulseis received from integrator 2 which pulse will then cause contact arm 82of switch 80 to move from contact 84 to contact 83.

FIGURE 5B is a schematic diagram of solenoid actuated relay switch 98 asit is connected in the apparatus of FIGURES 5 and 5A. When a signal isapplied to the coil of solenoid 98a through leads 190 and 97 (or 97a),contact 98b is closed thereby making a connection between line 188 andline 103. When there is no signal applied to the solenoid 98a, contact98b returns to its open position.

FIGURE 6 shows the relationship of cams 106 and 107 as they have rotatedthrough the three stages of each cycle of operation of this mechanism.In stage A double lob cam 106 and single lob cam 107 are in a positionso that no switching will occur until rotated 90 and 180, respectively.When motor 104 is operated for the first time cams 106 and 107 arerotated 90 at which time cam 106 trips switch 91 but cam 107 still has90 of rotation to follow through before it will trip switch 89. In stageC cam 106 is in position to trip a switch 91 back to the position it wasin in stage A while cam 107 has reached the first point where it is in aposition to trip switch 89 the first time. Thus, in a rotational arc of180, which is generally required by the metering device 5, cam 106 tripsswitch 91 twice while cam 107 trips switch 89 once to end the cycle.

In FIGURE 7 the pulse from integrator 2 passes to switch which has twocontacts 141 and 142. Switch 140 is connected through lines 143 and 144to switch which has two contacting arms 171 and 172 connected tocontacts 143 and 144 respectively and three contacts 173, 174, and 175.Contacts 173 and 175 are connected by electrical lines 176 and 177 toelectrical line 178. Line 178 is connected to solenoid 15011 which,along with operating rod 15% and valve 150c is a part of normally closedsolenoid valve 150. Contact 174 is connected through electrical line 179to timer motor 180. Line 73 is connected to timer motor 180 through line181 and to solenoid 150a through line 182. Shaft 183 attached to motor180 carries cam 184. Cam follower 185 coacts with cam 184 to trip switch170 back and forth between the three contacts. Air passes from a source(not shown) to pipe 151, valve 1500, pipe 152 into pneumatic actuator153. Actuator 153 contains a threaded shaft 154 with a piston 155coacting with the threaded portion and biased toward air inlet aperture156 by resilient means 157. Air is vented from actuator 153 through vent158. Shaft 154 is connected to shaft 159 by ratchet means 160. Shaft 159carries cam 161 and is attached to the rotatable member of meteringdevice 5. Cam follower 162 coacts with cam 161 and is adapted to tripswitch 140 back and forth from contacts 141 and 142.

In operation the pulse passing through contact 141 passes through line143, contact 173, and lines 176, 178, and 149 to operate solenoid 150aand open valve 150C and cause rotation of cam 161 through a 90 arc.After the 90 rotation cam follower 162 trips switch 140 to contact 142thereby deenergizing solenoid 150a, closing valve 150a and stoppingrotation of shaft 159 and passing the pulse through line 144, contact174 and line 179 to start operation of timer motor 180. After timermotor 180 rotates cam 184, cam follower 185 trips switch 170 therebymoving contacting arm 172 from contact 174 to contact 175 and causingthe pulse to pass through lines 177, 178, and 149 to reopen valve 150cand cause cam 161 to be rotated another 90 at which time switch 140 isretripped and the contact arm moved back to contact 141. Here also thetime required to cause cam 184 to rotate a sufiicient amount to tripswitch 170 is that amount of time required to allow the chamber in therotatable member of metering device to substantially completely emptyits contents. After switch 140 is retripped back to contact 141 andpulse that is left is employed through line 143, contacting arm 171,contact 174, and line 179 to continue operation of timer motor 180. Thefirst portion of the next pulse from integrator 2 is employed in likemanner until cam 184 is rotated to a position where it retrips switch170 so that contacting arm 171 and 172 are again in contact with contact173 and 174, respectively.

FIGURE 7A shows an alternative time delay device which can be used withthe apparatus of FIGURE 7 in place of switch 170, motor 180, cam 184,and cam follower 185. Contact 142 of switch 140 is connected throughline 146 to circuit delay device 147 and then through lines 148 and 149to solenoid 150a of normally closed solenoid valve 150. Contact 141 isconnected to solenoid 150a through electrical lines 145 and 149. Circuitdelay device 147 can be the same type of device as disclosed in FIG- URE5A.

In operation of the apparatus of FIGURE 7 utilizing the alternate delaymeans of FIGURE 7A, the pulse from integrator 2 initially passes throughcontact 141 and lines 143, 145, 148, and 149 to solenoid 150a whichopens valve 1500 and causes air to be admitted to actuator 153 for atime sufficient to push piston 155 the distance required to rotate shaft154 and 159 and ratchet 160* and cam 161 90 at which time cam follower162 trips switch 140 and transfers contacting arm to contact 142, thusdeenergizing solenoid 150a, closing valve 150c, and stopping rotation ofshaft 159. The pulse then passes through lines 144 and 146 into circuitdelay device 147 and after the time delay sufficient to allow contentsof the chamber of the rotatable member of metering device 5 to besubstantially completely removed therefrom, the pulse is passed by lines148 and 149 to reopen valve 150a and admit additional air to actuator153 thereby causing piston 155 to advance another distance sufficient tocause rotation of cam 161 sufliciently to cause cam follower 162 toretrip switch 140 and move the contacting arm back to contact 141 and tocomplete the 180 rotation of shaft 159 after which the duration of thepulse terminates and resilient means 157 forces the piston back towardthe inlet end 156 of actuator 153 which is accomplished withoutdisturbing the rotatable member in metering device 5 due to ratchet 160.

FIGURE 8 shows double lob cam 161 and the three stages of rotation ofeach cycle of operation. In stage A valve 150 is opened for the firsttime and cam 161 is then rotated to the position of stage B at whichstage cam follower 162 trips switch from contact 141 to contact 142.When valve reopens for the second time cam 161 is rotated another 90 tothat shown at stage C at which point switch 140 is retripped fromcontact 142 back to contact 141.

Example A 9 p.s.i.g. signal is fed into a Honeywell pulse transmitter(ie a variable duration pulse generator) Series 702E62N having a maximumpulse rate of 540 pulses per hour, from which generator is obtained anelectrical signal which is composed of a series of separate, electricpulses about 5 seconds in duration, the period of duration varyingproportionally as the pneumatic signal fed into the generator varies inpressure magnitude. This variable duration signal is fed into anIndustrial Timer Corporation recycling cam switch and a Cramer TypeTEC-lSS Style A time delay relay, the two components making up theintegrator. An output electric signal is obtained from the integratorwhich is composed of a series of electrical pulses each pulse of whichis 4 seconds. The start of each pulse is separated from the start ofeach preceding pulse by a time period of 13.3 seconds which time periodvaries proportionally with the increase or decrease of duration of theelectrical pulses fed into the integrator. The output signal from theintegrator is fed into a Westinghouse solenoid piloted air operated4-way valve Cat. No. PD4- 41-9398 which controls the air flow to aBettis Corporation Model 301 pneumatic rotary actuating mechanism with a180 ratchet coupling which in turn is mechanically coupled to a ballcheck metering device like that of U.S. 3,167,398. The actuatingmechanism in response to the signal from the integrator rotates thecaptive ball valve of the metering device through a cycle of rotation ofthe valve 90 in a given directionpause two seconds-rotation of the valvea second 90 in the same directionstop.

Reasonable variations and modifications are possible within the scope ofthis disclosure without departing from the spirit and scope thereof.

We claim:

1. A method for producing a cyclic mechanical motion from a first signalhaving a varying magnitude comprising producing an intermediate signalcomposed of a series of pulses each having a variable time duration andeach formed during one of a series of sequential time intervals, eachtime interval being of substantially equal length, the time duration ofeach pulse varying in length in response to variations in the magnitudeof said first signal, producing in response and in proportion to saidintermediate signal a resultant signal composed of a series of pulseseach having a substantially equal time duration and each pulse beingspaced from the other by a varying time interval, and utilizing thesubstantially constant time duration characteristic of the pulse of saidresultant signal to effect and control said cyclic mechanical motion.

2. The method according to claim '1 wherein said cyclic mechanicalmotion is a rotary motion suitable for rotating a valve means.

3. Apparatus for producing a cyclic mechanical motion from a firstsignal composed of a pulse having an indefinite and variable timeduration and a varying magnitude during that time duration comprisingvariable duration pulse generator means for producing an intermediatesignal composed of a series of pulses each having variable time durationand each formed during one of a series of sequential time intervals,each time interval being of substantially equal length, the timeduration of each pulse varying in length in response to variations inthe magnitude of said first signal, integrator means operably connectedto said pulse generator means for producing in response and inproportion to said intermediate signal a resultant signalin the form ofa series of pulses with substantially constant time durationcharacteristics occurring at varying time intervals, and actuating meansoperably connected to said integrator means for utilizing said resultantsignal to effect and control said cyclic mechanical motion.

4. The apparatus according to claim 3 wherein the cyclic mechanicalmotion effected is a rotary motion suitable for rotating a valve means.

5. In an apparatus adapted to rotate a member through a first finitearc, pause a finite length of time, and then rotate said member in thesame direction through a second finite arc, at least one cam meanscarried by said member and adapted to rotate therewith, at least oneswitch means associated with said at least one cam means, at least onecam follower engaging said at least one cam means, at least one switchactuating means operably connecting said at least one switch means andsaid at least one cam follower, means for passing signal to and throughsaid switch means, means for rotating said member, a time delay meanscircuit means operatively connecting said at least one switch means tosaid means for rotating said member both directly and through said timedelay means so that rotation of said member and said at least one cammeans causes alternate passing of said signal from said switch meansdirectly to said means for rotating said member and indirectly to saidmeans for rotating said member through said delay means therebyeffecting a first rotation of said member by operation of said rotationmeans for said member, a pause while said signal is passing through saidtime delay means followed by rotation of said member again when saidsignal is passed directly to said means for rotating said member.

6. In an apparatus adapted to rotate a member through a first finitearc, pause a finite length of time, and then rotate said member in thesame direction through a second finite arc, a pair of cam means carriedby said member adapted to rotate therewith, a pair of cam followers, oneengaging each said cam means, a first and a second twopositionelectrical switch means, means operably connecting said cam followers tosaid first and second switch means enabling said first and second switchmeans to be switched back and forth by said cam followers, a twopositionlatching relay, a first electrical power supply means connected to saidlatching relay, means for switching said relay to the opposite positionwhen an electrical signal is passed thereto, means for passing anelectrical signal thereto, electrical conduit means connecting eachposition of said latching relay to a position of said first switchmeans, an electrical conduit connecting said first and second switchingmeans, an electrical signal time delay means, a normally open thirdelectrical switch means, a second electrical power supply meansconnected to said third switch means, means for closing said thirdswitch means when an electrical signal is impressed thereon, anelectrical means for rotating said member, means for passing electricalcurrents from said third switch means to said means for rotating saidmember, an electrical conduit means directly connecting one position ofsaid second switch means to said third switch closing means, electricalconduit means connecting the other position of said second switch meansto said third switch closing means through said time delay means, saidpair of cam means being orientedrelative to one another and of suchrelative configuration that said first switch means is switched by itsassociated cam once during a total arc of rotation equal to the sum ofthe separate before-mentioned arcs while said second switch means isswitched by its associated cam twice during said total arc of rotation,once during each separate before-mentioned are so that said secondswitch means passes an electrical signal received from said first switchmeans alternately directly to said third switch closing meansandindirectly to said third switch closing means through said time delaymeans.

7. The apparatus according to claim 6 wherein said time delay meansincludes a switching means operatively connected to said second switchmeans and a timing motor and cam means associated with said switchingmeans and adapted to trip said switch means in a manner to thereby passthe electrical signal received by said switch means alternately directlyto said third switch closing means and indirectly to said third switchclosing means through said time delay means.

8. In an apparatus adapted to rotate a member through a first finitearc, pause a finite length of time, and then rotate said member in thesame direction through a second finite arc, a cam means carried by saidmember and adapted to rotate therewith, a two-position electrical switchmeans, a cam follower engaging said cam means, means connecting said camfollower to said two-position switch means allowing said switch to beoperated between its two positions by said cam followers, means forpassing an electrical signal to and through said switch means, pneumaticmeans for rotating said member upon application of an electric signal tosaid pneumatic means, electric conduit means operatively connecting oneof said positions of said switch means to said means for rotating saidmember, an electric signal time delay means, electric conduit meansoperatively connecting the other of said positions of said switch meansthrough said time delay means to said means for rotating said member,said cam means being adapted to switch said switch means from oneposition to the other and back again during rotation of said memberthereby causing a signal to alternately pass directly to said means forrotating said member and indirectly to said means for rotating saidmember through said delay means.

9. The appartus according to claim 8 wherein said means for rotatingsaid member comprises a ratchet means and a pneumatically actuatedpiston engaging said member through said ratchet means, said pneumaticactuator being controlled by a solenoid valve means which alternatelyreceives the pulse from the switching means and the time delay means andupon receipt of each pulse opens and admits air to said pneumaticactuator thereby causing rotation of said cam means; and wherein saidtime delay means comprises a timing motor having a rotatable shaft, atwoposition switch means operatively connected to said timing motor, acam follower, a cam means in contact with and operating through said camfollower to trip said switch means back and forth between its twopositions thereby alternately passing the pulse directly to saidsolenoid valve means and indirectly to said solenoid valve means throughsaid timer motor.

References Cited UNITED STATES PATENTS 3/196Q Hosea et al 318-443 3/1964Lessig 3l8443 U.S. Cl. X.R. 3l8486

